In Brazil, user @helio-lourencini has the only two iNat observations of Zethus miniatus with its communal nest, a most interesting behavior. It has been identified by @rblopes with the following explanation:

"This species seems to be common in Brazil, although I never got a glimpse of the nest in the wild; only in collections and pictures. It has been reported by Ducke in the early 1900s to have communal nesting (they build the nest together, but each female tends to their own offspring, there is no cooperative brood care). Closely related species like the Central American Z. olmecus may present a similar behavior, since their nests do look alike, but nothing has been officially published, as far as I know. Understanding the evolution of this type of nesting was part of a Post-doc project of mine, but lack of nests from other species complicated the study."

https://www.inaturalist.org/observations?verifiable=true&taxon_id=883640&place_id=&preferred_place_id=1&locale=en-US

Addendum: Rogério informs me that the nest is not made of mud, a I had assumed: “It is made of mastigated vegetable matter. In this case and in most other Zethines, the main building material is foliage.”